1. Field of the Invention
The present invention relates to a process for the consolidation of formations, in particular, sand. More specifically, the present invention relates to a process for consolidating formations encountered during the drilling of an oil well, at the same time maintaining the permeability of the consolidated zones.
2. Discussion of the Background
It is known that the presence of sand in an oil well causes great drawbacks, for example blocking of the oil flow (or gas) and damage to the equipment used for the drilling.
Patent literature describes various methods for consolidating sand encountered during the drilling of a well.
For example, U.S. Pat. No. 3,481,403 describes a process for the consolidation of sand which comprises the injection of an alkyl ether and subsequently a resin. There are other variations in literature which are always based on the use of various kinds of resins.
All processes using resins are particularly complex and delicate as the above compositions must be prepared with very strict procedures and may therefore be ineffective in the presence of unexpected contaminations.
Another disadvantage of the use of resins consists in the high viscosity (&gt;20 cP) of their solutions to be injected into the formation, a viscosity which prevents the treatment of formations having permeabilities of less than 50 mD.
Another method used for consolidating sand consists in the use of sodium silicate together with various "setting" agents, as described in U.S. Pat. No. 1,421,706 and U.S. Pat. No. 3,175,611.
Also the use of sodium silicate however has disadvantages, in particular a reduction in the permeability of the consolidated formation.